Corrosion-resistant alloy



at. 27, 1923. V

WESILEY J. BECK AND JAMES A. AUPPERLE, OF MIDDLETOWN, OHIO, ASSIGNQRS TO THE AMERICAN ROLLING MILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORA- 'I'ION OF OHIO.

No Drawing.

T 0 all whom it may cancer/t:

Be it known that we, \Vnsnnr J. BECK and JAMES A. AUPPER'LE, citizens of the United States, and residents of Middletown, in the county of Butler and State of. Ohio, have invented a certain new and useful Corrosion- Resistant Alloy. of which the following is a full, clear. and exact description.

Our invention relates to iron alloys of the general characteristics adaptable for structural purposes under exposure to the atmosphere and underground, as for example, for smoke stacks and pipes, tank plates. metal roofing. flumes and the like. It has as its object the provision of a. material of these characteristics, which, in its natural. uncoated condition, gradually provides itself with a corrosion resistant coating as will be described. I

lVe have discovered that silicon, which has the known property of reducing the amount of oxygen in iron and steel when added to them while they are in a molten condition, also possesses this characteristic at atmospheric temperatures in its action upon the oxides formed upon the surface of these metals through comparatively long periods of time, when present in iron in substantial quantities. Vi e have discovered that iron containing substantial quantities of silicon will, when exposed to natural proc esses of corrosion under conditions where air predominates, provide itself with a coating dissimilar in all of its characteristics from the coating ordinarily produced upon the surface of iron or steel, and that this quality can. be produced without impairing the rollability and workability of the material. Rapidly rusting material when exposed to the atmosphere takes on a light colored or reddish rust which is loosely adhercut and of a sand-like nature. The rust consisting very largely of ferric oxide (Fe O e have discovered that iron substantially alloyed with silicon will when exposed to the natural processes of oxidation. take on a dense velvetylike protective coating tightly adherent to the metal. this coating consisting very largely of the black magnetic oxide of iron (Fen, 11 0,), together with silicate of iron, the silicon in the alloy having the property of preventing the format-ion of the higher oxides upon the surface of the metal] We have discovered further that this coating is of an enamel-like Application filed March 19, 1919. Serial No. 283,581.

quality which when once formed positively protects the base metal, and, moreover, that the breaking of this coating results merely in the replacement of another like coating on the newly exposed base metal. It has long been known that the magnetic oxide of iron produced at high temperatures upon the surface of ordinary iron and steel will prevent corrosion. Ordinarily iron and steel coated with the magnetic oxide of iron produced at high temperatures will take on a reddish sand-like rust where the coating becomes broken, whereas when the magnetic oxide of iron eventually produced on our new allov at ordinary temperatures, is broken our alloy will not produce the reddish sand-like rust (largely composed of ferric oxide 1e 0,), but will again produce the black, dense, velvety, closely-adherent coating, consisting largely of the magnetic oxide of iron (FeO, Fe O,), where the original coating had been broken.

In making this alloy it can be produced by either the acid or basic Bessemer, openhearth, electric furnace, or crucible processes. The refining of the metal is preferably carried to the same degree as is ordinarily practiced in the production of mild steel. As is the usual practice in the manufacture of ordinary steel, enough manganese can be added to themetal either in the furnace or in the ladle to produce the desired working qualities/ The silicon is preferably added as a ladle" charge, otherwise the sili con would have a tendency to react with the slag. The amount of silicon in the final metal may vary from around two per cent, which will give some results, up to whatever per cent will admit of working the alloy into the desired'shape to produce the desired rolling and forging qualities and ductility, or as expressed in general terms workability. of course the metal may be cast into shapes. and will still be of workable quality where it has not that brittleness or glassiness which would prevent forging, rolling or drawing. \Ve do not wish to'liinit our invention to forms that are rolled, forged or drawn, but to defining the quality of the metal of which the forms are composed, no matter how they are made up. \Ve prefer to employ from two per cent to four and one-half per cent, although with other metals in the alloy and special treatment the amount may be increased above this. These per cents refer to the amount of silicon in the. finished product.

The ladle charge of silicon serves as a le oxidizing and degasifyihg agent, so, that our alloy will contain ordinarily less than three hundredths per cent in the aggregate of oxygen, carbon monoxide and nitrogen. This degasitication gives our. product the property to overcome COII'OSiOii due to the absence of pockets of gas which through long periods of time would diffuse through the metal and break the protective coating.

We obtain our percentages by a process of our own. asfollows: the percentage of oxygen and -arbon monoxide is obtained by heating clean borings in an atmosphere of pure hydrogen gas and absorbing the water formed from the combination of hydrogen and oxygen. The amount of carbon monoxide is obtained sin'mltaneously to the above through the oxidizing of the carbon monoxide to carbon dioxide with the use of iodine pentoxide at elevated temperatures, and then absorbing the carbonic acid gas formed in barium hydroxide.

The working of our alloy. together with the heat treatments are the same as used and known to the art for providing the desired shapes and characteristics of ductility. malleability. or stiffness in the finished product. 7

This product is valuable in any conditions where exposure would produce oxidation upon the surface. It is usable for example. in the manufacture of wire. and as stated in the manufacture of sheets or plates for use in the construction of buildings. metal lath. rods or pipes for conduction of flowing media. and generally for use where corrosion must be combated. It is particularly valuable where the metal is to be used in an uncoated condition.

The coating produced on our alloy when exposed to conditions where oxygen predominates is different from the coating produced on even the highest grades of iron or steel: the coating is more cement-like in its quality. it is more magnetic. darker in color. more firmly attached to the metal. and is therefore inherently impervious to moisture.

By the words iron alloys in the appended claims. we do not intend to limit ourselves to alloys containing iron and silicon only, as the alloy might contain nickel, copper, cobalt, manganese, carbon, arsenic, or any other of the usual alloying constituents together or separately.

Having thus descrila-d our invention, what we claim as new and desire to secure by Letters Patent, is:

'l. A workable iron alloy highly resistant to destructive corrosion under atmospheric conditions. and fabricated into forms for use under exposure to such conditions. containing silicon ranging upward from substantially two per cent to a percentage not so high as to render it unworkable and containing more silicon than any other alloying metal.

.2. A workable iron alloy highly resistant to destructive corrosion under atmospheric conditions, and fabricated into forms for use under exposure to such conditions. containing silicon ranging from around two percent up to around four and one-half per cent and containing more silicon than any other alloying metal.

3. workable iron alloy highly resistant under exposure to rusting conditions where air predominates. and fabricated into forms for use umler such exposure. containing a substance. which. upon oxidation of the iron. acts to produce a closel adherent coating of black oxide instead of a red oxide.

4. work: ble iron alloy highly resistant under exposure to rusting use under such exposure. containing a substance which. upon oxidation of the iron. acts to produce a closely adherent coating of black oxide instead of a red'oxide by exerting a deoxidizing action on the red oxide normally produced upon such exposure.

workable iron alloy highly resistant. under exposure to rusting conditions where air predominates. and fabricated into forms for use under such exposure. containing a. substance which. upon oxidation of the iron. acts to produce a closely adherent coating of black oxide instead of a-red oxidev by exerting a deoxidizing action on the red oxide norinally produced upon such exposure. said substance comprising silicon.

\VFSLICY J. BECK. .T.\ .\ll$ A. AUPPERLE. 

